FIG. 1 shows a prior art AV (audio and video) terminal 1 which includes a ground end, a lift sound channel and a right sound channel. A front end of the insertion terminal 1 is an insertion rod 10 having a three sectional insulating contact surface. The insertion rod 10 is connected to a tube seat 11 at a rear end. The insertion terminal 1 is only used to a connecting joint a microphone or a single AV insertion. It has no other usage. Moreover it is difficult to form the three sectional insulating contact surface and thus the cost is high.